Part 10a Flashcards
digestive enzymes that are secreted by SI to partially hydrolyze proteins
trypsin, chymotrypsin
prob of trypsin/chymo inhibitors?
as anti-nutritional factors, have risk of reducing dietary protein digestibility, contributing to nrg reduction and reduced bioavailability of essential a.a., possible toxicity
where are T/C inhibitors found?
seeds of grain legumes (pulse/oilseed legumes), barley, squash, peanut, corn, potato
functions of protease inhibitors in plants?
storage protein, defense mech against insects and herbivores
how to inactivate these inhibitors?
moist heat treatments (100 degrees for 3-10 min), plant breeding and gene engineering to reduce lvls of these–>dry heat NOT effective
toxicity of protease inhibitors?
reduced N and S absorb, reduce bioavailability, reduce GR, protein malnutrition, induce pancreatic hypertrophy, possible pancreatic cancer
benefits of protease inhibitors?
genetically engineered into plants as biological control agent, and anti-carcinogenic (block ROS form, deprive cancer cells of a.a.)–>breast cancer treatment?, provide additional nutr value when denatured , role in AIDS treatment
how does virus in AIDS become active?
thru aspartic acid protease
also known as lectins, these are plant glycoproteins found in lots of seeeds, veg, fruit, virus, bacteria, moulds
hemagglutinins
what is role of hemagluttinins?
not known, maybe in insect resistance, CHO storage, translocation
how to inactivate hemagluttinin?
moist heat treatment
toxicity of hemagluttinin?
resistant to stomach acid, bind to CHO in RBC–>agglutination–>anemia, kidney failure, bind to intestinal epithelial cells and interfere with nutr absorption, destroy villi, abnormal G and D, lesions permit intestinal bacteria to enter blood
how is agglutination diff from clotting?
remain fluid, but hit kidney and can’t filter
type of hemagglutinin used as poison
ricin (castor beans)
glycoproteins that inhibit activity of mammalian alpha amylase in SI
amylase inhibitors
what does alpha amylase do?
it hydrolyzes starch to produce gluc and maltose, which are readily absorbed
amylase inhibitors found in:
kidney beans
amylase inhibitors used as:
dietary suppplement for wt loss, GI lowering, diabetes treatment
fxn of amylase inhibitors in plants?
insect resistance, impede starch digestion
how to inactivate amylase inhibitors?
moist heat treatment
prob of amylase inhibitors?
reduce bioavailability of important nrg for humans (v growth, organ wt changes (liver and pancreas)
benefits of amylase inhibitors?
genetically engineered into plants as bio control agents to combat insect damage
sulfur containing carbs contained in cabbage, cauliflower, broccoli, radish, mustard, rapeseed, turnips, brussels sprouts
glucosinates (thioglucosides)
toxicity of glucosinates?
breakdown products are goitrogens
what is goitrogens?
comps that cause ^ thyroid–>goitre, can’t make hormone properly
toxicity of nitriles?
acute toxicity (HCN)–>inhibit cytochrome oxidase required in e- transport–>organ damage; also bind to glutathione which inhibits ROS removal from cells; hemorrhaging and necrosis of adrenal cortex
toxicity of isothiocyanates?
goitrogenic, inactivate enzymes in CHO metabolism path, react with sulfhydryl groups on proteases and make them inactive; cancer?
____ isothiocyanate is a teratogen
allyl
benefits of isothiocyanates?
phytochemical to inactivate carcinogens and protect cells from DNA damage, anti-inflammatory/antiviral/antibacterial, treat insomnia?
toxicity of toxic a.a.?
enzyme inhibition as “suicide substrates”–>reduced cell transport of essential chem comps, probs with protein synth, help toxins move across BBB, reproductive disorders
why is safety of free range questionable?
toxic a.a.s concentrated in seeds of forage grains/legumes–>transferred to humans when consume animal tissue
examples of toxic a.a.?
mimosine (like tyrosine) and canavanine (like arginine)
toxicity of beta-cyanoalanine
iathyrogen–>neurolathyrism (neuro disorder)–>musc rigid, crippling paralysis, death
Brazil nuts have lots of these toxic a.a.
selenocysteine and selenomethionine
selenium poisoning characterized by:
severe hemolytic anemia, kidney/liver/heart damage
benefits of “toxic’ a.a.?
anti-tumor (disrupt mitosis), treat Parkinson’s (not beta-cyanoalanine), antiox (mimosine–phenolic), antimicrobial that is broad spectrum by impairing protein synth
group of chem comps that may release HCN upon metabolism/decomp
cyanogens
cyanogens naturally present in many plant species as _____
cyanogenic glucosides
example of cyanogen found in cassava?
linamarin
cyanogens found in almonds
amygdalin/laetrile
how does cyanogenesis occur?
reactants come in contact only after phys. disruption of cells by bruising/cutting
cyanide has strong affinity for ____ which causes disrupt cell resp–>death
cytochrome oxidase
secondary metabolites derived from a.a. (basic or aromatic), like lysine/ornithine; tryptophan
alkaloids
alkaloids found in about ___% of all plants
40
toxicity of alkaloids?
strong anticholinesterase activity–>block Ach breakdown–>bradychardia; disrupt mem fxn in GI tract (lesions, hemorrhage, death); disrupt mitosis (growth, mutations, cancer); resp depression; cardiac arrest; neuromusc blockage (numb, weak)
___ is 15% morphine
latex
example of alkaloids in green potatoes?
solanine
characteristics of solanine?
limited water sol, heat stable, cholinesterase inhibitor and causes GI lesions, ingestion symptoms include diarrhea, drowsy, vomiting
example of alkaloids found in peel of green tomatoes
tomatine (glycoalkaloid)
common alkaloid in coffee?
caffeine
Denmark eat lots of ___
chocolate!
what is acute lethal dose of caffeine?
10g
what is caffeinism?
> 500mg/day–>restless, anxious, irritable, musle tremor, insomnia, headache, GI probs
caffeine blocks _____ receptors that is necessary for slowing down (breaking action, sleep and proper oxygenation)
adenosine (CNS)
benefits of caffeine?
increased alert, vigilant, vigour, mood improve
example of alkaloid in chocolate?
theobromine (very structurally similar to caffeine–just methyl grp)
secondary plant metabolites synth thru acetate and shikimate pathways–>Phe and Tyr, naturally occuring polyphenolic comps with molecular mass 300-3000
tannins
catechins and epicatechins found in:
fruits, tea, red wine, chocolate
what is most abundantly consumed phenolic?
quercitin
hydrolyzable tannins contain a central ____ + polyphenols
carbohydrate (usually D-glucopyranose) covalently linked to gallic acid residues
what are condensed tannins?
don’t contain CHO moiety (most abundant form in nature)
example of condensed tannins?
proanthocyanidins, lignin (abundant cuz of stability)
toxicity of tannins?
cross link with proteins/DNA/RNA–>structure change cause fxn change; carcinogenic; reduced wt gain and egg production (reduced protein absorption); digestive enzyme inhibition
physical removal of tannins?
dehulling of grains
chem treatment of tannins?
steam/alkali treatment (prob of nutrient destruction, colour formation, off flavour)
tannin functions in plants
repaire damaged tissue, chem defense (metabolic arrest, cell div inhibition)
why repair damaged tissue?
prevent microbial growth and insect infestation, reduce water loss, animals don’t like astringent taste (rough, dry, chalky)
tannins used to help:
gut health, antimicrobial for vag health, immune boost, liver health, ^ vision, wrinkle relaxer
tannins found in this important food crop
sorghum
benefits of sorghum:
cals, nutr, antioxidant
limitations of sorghum:
rich in tannins, poor essential a.a. content esp. lysine
sorghum used for:
porridge, unleavened bread: major processing step is boiling–>used as ethanol and animal feed for US
new method for evaluating protein quality
DIAAS
how reduce tannins ?
genetic engineering
triterpenes (C30) that are norm covalently linked to CHO (glycoalkaloid) that exhibit foaming/emulsifying properties (surface active agent)
saponins
saponins found in:
asparagus, beets, peanuts, potatoes, spinach, legumes
toxicity of saponins:
powerful haemolyzing agents (RBC, liver, kidney necrosis)–>GI probs, vomit, cramps, fever, jaundice, paralysis, teratogen
possible benefit of saponins?
; readily excreted intact cuz not absorbed, so possible toxic comp removal? Not issue in humans really
other naturally occuring toxic comps in foods?
gossypol, sesamol, eugenol, coumarin
